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Carbohydrate availability and muscle energy metabolism during intermittent running.
Med Sci Sports Exerc. 2008 Jan; 40(1):96-103.MS

Abstract

PURPOSE

To examine the influence of ingesting a carbohydrate-electrolyte (CHO-E) solution on muscle glycogen use and intermittent running capacity after consumption of a carbohydrate (CHO)-rich diet.

METHODS

Six male volunteers (mean +/- SD: age 22.7 +/- 3.4 yr; body mass (BM) 75.0 +/- 4.3 kg; V O2 max 60.2 +/- 1.6 mL x kg(-1) x min(-1)) performed two trials separated by 14 d in a randomized, crossover design. Subjects consumed either a 6.4% CHO-E solution or a placebo (PLA) in a double-blind fashion immediately before each trial (8 mL x kg(-1) BM) and at 15-min intervals (3 mL x kg(-1) BM) during intermittent high-intensity running to fatigue performed after CHO loading for 2 d. Muscle biopsy samples were obtained before exercise, after 90 min of exercise, and at fatigue.

RESULTS

Subjects ran longer in the CHO-E trial (158.0 +/- 28.4 min) compared with the PLA trial (131.0 +/- 19.7 min; P < 0.05). There were no differences in muscle glycogen use for the first 90 min of exercise (approximately 2 mmol of glucosyl units per kilogram of dry matter (DM) per minute). However, there was a trend for a greater use in the PLA trial after 90 min (4.2 +/- 2.8 mmol x kg(-1) DM x min(-1)) compared with the CHO-E trial (2.5 +/- 0.7 mmol x kg(-1) DM x min(-1); P = 0.10). Plasma glucose concentrations were higher at fatigue in the CHO-E than in the PLA trial (P < 0.001).

CONCLUSIONS

These results suggest that CHO-E ingestion improves endurance capacity during intermittent high-intensity running in subjects with high preexercise muscle glycogen concentrations. The greater endurance capacity cannot be explained solely by differences in muscle glycogen, and it may actually be a consequence of the higher plasma glucose concentration towards the end of exercise that provided a sustained source of CHO for muscle metabolism and for the central nervous system.

Authors+Show Affiliations

Institute of Food, Nutrition and Human Health, Massey University, Auckland, New Zealand. a.foskett@massey.ac.nzNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Journal Article
Randomized Controlled Trial

Language

eng

PubMed ID

18091017

Citation

Foskett, Andrew, et al. "Carbohydrate Availability and Muscle Energy Metabolism During Intermittent Running." Medicine and Science in Sports and Exercise, vol. 40, no. 1, 2008, pp. 96-103.
Foskett A, Williams C, Boobis L, et al. Carbohydrate availability and muscle energy metabolism during intermittent running. Med Sci Sports Exerc. 2008;40(1):96-103.
Foskett, A., Williams, C., Boobis, L., & Tsintzas, K. (2008). Carbohydrate availability and muscle energy metabolism during intermittent running. Medicine and Science in Sports and Exercise, 40(1), 96-103.
Foskett A, et al. Carbohydrate Availability and Muscle Energy Metabolism During Intermittent Running. Med Sci Sports Exerc. 2008;40(1):96-103. PubMed PMID: 18091017.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Carbohydrate availability and muscle energy metabolism during intermittent running. AU - Foskett,Andrew, AU - Williams,Clyde, AU - Boobis,Leslie, AU - Tsintzas,Kostas, PY - 2007/12/20/pubmed PY - 2008/2/28/medline PY - 2007/12/20/entrez SP - 96 EP - 103 JF - Medicine and science in sports and exercise JO - Med Sci Sports Exerc VL - 40 IS - 1 N2 - PURPOSE: To examine the influence of ingesting a carbohydrate-electrolyte (CHO-E) solution on muscle glycogen use and intermittent running capacity after consumption of a carbohydrate (CHO)-rich diet. METHODS: Six male volunteers (mean +/- SD: age 22.7 +/- 3.4 yr; body mass (BM) 75.0 +/- 4.3 kg; V O2 max 60.2 +/- 1.6 mL x kg(-1) x min(-1)) performed two trials separated by 14 d in a randomized, crossover design. Subjects consumed either a 6.4% CHO-E solution or a placebo (PLA) in a double-blind fashion immediately before each trial (8 mL x kg(-1) BM) and at 15-min intervals (3 mL x kg(-1) BM) during intermittent high-intensity running to fatigue performed after CHO loading for 2 d. Muscle biopsy samples were obtained before exercise, after 90 min of exercise, and at fatigue. RESULTS: Subjects ran longer in the CHO-E trial (158.0 +/- 28.4 min) compared with the PLA trial (131.0 +/- 19.7 min; P < 0.05). There were no differences in muscle glycogen use for the first 90 min of exercise (approximately 2 mmol of glucosyl units per kilogram of dry matter (DM) per minute). However, there was a trend for a greater use in the PLA trial after 90 min (4.2 +/- 2.8 mmol x kg(-1) DM x min(-1)) compared with the CHO-E trial (2.5 +/- 0.7 mmol x kg(-1) DM x min(-1); P = 0.10). Plasma glucose concentrations were higher at fatigue in the CHO-E than in the PLA trial (P < 0.001). CONCLUSIONS: These results suggest that CHO-E ingestion improves endurance capacity during intermittent high-intensity running in subjects with high preexercise muscle glycogen concentrations. The greater endurance capacity cannot be explained solely by differences in muscle glycogen, and it may actually be a consequence of the higher plasma glucose concentration towards the end of exercise that provided a sustained source of CHO for muscle metabolism and for the central nervous system. SN - 0195-9131 UR - https://www.unboundmedicine.com/medline/citation/18091017/Carbohydrate_availability_and_muscle_energy_metabolism_during_intermittent_running_ L2 - http://dx.doi.org/10.1249/mss.0b013e3181586b2c DB - PRIME DP - Unbound Medicine ER -